1. Field of the Invention
The invention concerns a method for recognizing in a pre-established catalog of stars in the sky some or all of the stars detected by a star sensor, for a processing system using star recognition.
2. Background of the Invention
If recognition is successful, it is possible, for example, to estimate the attitude of the frame of reference of the star sensor or, using additional means, to refine an estimate, from which it is then possible to work back to the attitude of the vehicle, for example an aircraft or a submarine, on which the star sensor is mounted.
Prior art star recognition methods include methods in which:
some stars are selected from the sensed stars, the stars selected in this way being referred to hereinafter as "detected" stars; PA1 the detected stars are combined two by two into "detected doublets"; PA1 "likely doublets" are identified, i.e. doublets of stars from the catalog which are in the vicinity of the detected doublets in a common characterization space; PA1 pairs are created each comprising a star of a likely doublet and a detected star, and PA1 at least one list of such pairs is supplied to the processing system. PA1 the stars from the catalog are grouped into classes, two stars being considered to belong to the same class if and only if they are coincident or there is a path which links them, a path being a series of likely doublets such that any pair of consecutive doublets of the series has at least one star in common, PA1 lists are established class by class by matching some or all of the stars of a class with detected stars to constitute a list, and PA1 at least one of these lists is selected and supplied to the processing system.
One such process is described in the paper "Autonomous Star Tracker Development" by R. W. H. van Bezooijen published in the proceedings of the Automatic Control In Aerospace IFAC Symposium, Tsukuba, Sep. 7, 1992.